a58 NATURAL HISTORY OF PLANTS. 



Gynœcium, ovules, &c, of Betula. Fruit dry, compressed, wingless, 

 or surrounded by a membranous wing, indéhiscent ; seed generally 

 1 (of Betula). — Trees or shrubs ; leaves alternate ; vernal floration 

 preceding or simultaneous (Pliijllothijrsus, Clethropsis) with leaves ; 

 scales of male catkins peltate, 5-bracteolate, 1- or oftener 3-florous ; 

 scales of female catkins cuneiform, shortly (from adnate bracteoles) 

 4-5-lobcd, incrassate above, at maturity separating from each other, 

 not deciduous, lignescent ; cones short. (Temp, and frigid regions 

 of both tvorlds, temp. South America, South Africa.) — See p. 223. 



II. CORYLEtE. 



3. Corylus T. — Flowers amentaceous monoecious ; males naked ; 

 stamens 4-8 (very rarely 2, 3), inserted within scales of catkin ; 

 filaments short free ; anthers 1-locular (or 2-locular; cells separate), 

 extrorsely rimose. Female flowers 2-nate budlike in axils of bracts 

 of catkins ; receptacle saclike, enclosing inferior adnate germen, with 

 very short annular epigynous calyx ; style branches 2, linear 

 elongate, densely stigmatose papillose. Ovules in cells 2 solitary 

 (or more rarely 2-nate) descending ; micropyle extrorsely superior. 

 Nuts more or less ligneous, 1-locular; walls very thick medullose 

 below. Seed generally by abortion 1 ; cotyledons of thick exalbu- 

 minous embryo fleshy plano-convex, epigeous at germination ; 

 radicle short superior and united to base of cotyledons. — Small trees 

 or shrubs ; leaves alternate dentate or penninerved, in vernation 

 longitudinally plicate as to the central nerve, and hence on one side 

 facing axis ; stipules caducous ; catkins precocious ; bracts of males 

 cuneiform, generally covering 2 bracteoles, connate within (some- 

 times 0) ; female catkins short subsessile, finally stipitate to elongate 

 foliate ramule ; each fruit surrounded by a sacciform accrescent 

 bracteole at sometimes open tubular apex dentate, laciniate or 

 spinescent, very rarely (Ostryopsis) with external accrescent scale, 

 divided within. (Northern temperate regions of both hemispheres). 

 —See p. 225. 



4. Carpinus T. — Flowers nearly of Corylus ; the males consisting 

 of stamens oo (3-20) inserted in axil of bracts of catkin ; filaments 

 slender 2-fid ; anther cells separate, pilose at apex and extrorsely 



